The effect of season of birth on the morphometrics of newborn Belgian Blue calves.

Breed type and environmental factors such as breeding season may have a significant impact on neonatal morphometrics. We followed a total of 236 elective cesarean sections in Belgian Blue (BB) cows, from which neonatal calves were morphometrically assessed (in cm) within the first 72 h of delivery using a strictly standardized protocol. The effect of the season of birth on each calf measurement was analyzed using mixed linear regression models, including the farm of origin as a random effect. Calves born in spring had a longer diagonal length (69.7 ± 1.24; P = 0.05) than those born in autumn (66.9 ± 1.16). The tibial length of calves born in spring (35.8 ± 0.48) was longer (P < 0.02) than of those born in autumn (33.1 ± 0.57) or summer (34.1 ± 0.49). Calves born in autumn have a shorter head diameter (12.9 ± 0.23; P < 0.02) than those born in summer (12.6 ± 0.29) or winter (13.5 ± 0.22). For all other parameters, no differences were found (P > 0.08). Based on the results of this study, it can be concluded that the birth season influences the morphometrics of neonatal BB calves, with a tendency for spring to be associated with the largest body size. The latter is important to avoid dystocia when BB cattle are crossed with other breeds.